Research On Method Of The State Of Charge Estimation Of Lithium-Ion Battery

The research and development of battery management system(BMS)is considered to be an important part of electric vehicles.The state of charge(SOC)estimation has always been the core component in battery management system,which is important to improve vehicle performance and battery life.This paper take advantage of battery to research on the estimation strategy of SOC.Firstly,the article makes a brief introduction to the background,and analyzes the relevant key technology of the battery management system.The factors influencing the SOC are analysed,and compares the pros and cons of the SOC estimation method,then a clear algorithm of electric cars are sured.Starting from the lithium-ion battery works by building a battery test experimental platform to analyze the voltage characteristics,charge and discharge characteristics,temperature characteristics and resistance characteristics of lithium-ion battery.This provide data to estimate the battery status and extended battery life.The paper analyzes and compares several popular models,then establishs a lithium-ion battery equivalent circuit model,and get the battery model's parameters and simulation model,the results shows that the model has high accuracy,can accurately simulate the lithium-ion battery dynamic characteristics.The thesis does research on the SOC estimation algorithm of Lithium-ion batteries which based on Extended Kalman Filter(EKF).A state-space model of the battery is proposed.In order to improve the accuracy of estimation,the open circuit voltage SOC estimation using as the initial value.Not only solved the SOC estimation problem of a long time,but also improve the accuracy of the open circuit voltage,thereby increasing the SOC estimation accuracy.The results show that this method solves the problem of estimating the initial error is large due to variation of the initial value and improve the overall estimation accuracy.